[0001] The present invention relates to a method of printing on a thermal medium by aligning
a test pattern. More particularly, the present invention relates to a method of printing
on a thermal medium by aligning print starting positions at a first surface and a
second surface of the medium, which is used in a thermal printer.
[0002] A method of printing on a thermal medium by aligning print starting positions at
a first surface and a second surface of the medium is known from
US 2001/022609 A1. Such a method aligns print starting positions at a first and a second surface by
detecting an edge of the medium.
[0003] A thermal printer can be divided into a type of printer that uses a medium that represents
a predetermined colour by responding to heat (hereinafter, referred to as thermal
medium), and a type of printer that uses an ink ribbon that transfers a predetermined
colour onto a general medium responding to the heat in order to print images on the
general medium. The ink ribbon type of printer uses a driving device for operating
the ink ribbon, thus it has a more complex structure and a correspondingly higher
price. Also, the ink ribbon needs periodic replacement, which increases the per page
printing price.
[0004] Referring to Figure 1, a thermal medium 10 includes a base sheet 11 having two surfaces,
that is, a first surface 10a and a second surface 10b, on which ink layers of predetermined
colours are respectively formed. The ink layers are formed to have different colours
from each other. For example, a yellow (Y) layer and a magenta (M) layer are sequentially
stacked on the first surface 10a, and a cyan (C) layer is formed on the second surface
10b. It is desirable that the base sheet 11 is formed of a transparent material. Reference
numeral 13 is a reflective layer that reflects light so that a colour image can be
seen on the first surface 10a. An example of the thermal medium 10 is disclosed in
U.S. Patent No. 6,801,233, which is assigned to the Polaroid Corporation.
[0005] The thermal printer using the thermal medium 10 uses a thermal printhead (TPH), in
which heating elements are disposed perpendicular to the direction in which the printing
sheet is fed. To perform dual-surface printing using one TPH, the printing process
for the first surface 10a of the medium 10 is performed, and then, the printing process
for the second surface 10b of the medium 10 is performed again using the same TPH.
When the two surfaces are printed, a colour image can be seen on the first surface
10a.
[0006] Figure 2 is a view illustrating a structure of a conventional thermal printer. Referring
to FIG. 2, the thermal printer includes a feeding roller 2 that conveys the thermal
medium 10, a platen 3 supporting a surface of the medium 10, and a TPH 4 forming an
image on the medium 10 that is disposed on the platen 3. A printer having one TPH
4 typically prints on both surfaces of the medium 10 in sequential order by rotating
the medium 10 or the TPH 4. Reference numeral 5 is an idle roller that pushes the
medium 10 that passes between the idle roller 5 and the feeding roller 2 toward the
feeding roller 2.
[0007] In the case where the TPH is not aligned with the medium when the TPH is rotated
for printing images on the second surface after printing images on the first surface,
the colour printing operation can produce misaligned printed images on the second
surface.
[0008] Therefore, a method of aligning a print starting position of the medium is required
when the first and second surfaces of the medium are printed.
[0009] The present invention provides a method for printing a thermal medium that is used
in a thermal printer by aligning the print starting position.
[0010] According to an aspect of the present invention, there is provided a method for printing
a thermal medium by aligning image, the method comprising the steps of (a) defining
a predetermined print starting position (SP) on a thermal medium (10) a predetermined
distance from one edge (FE) of the thermal medium (10); (b) feeding said thermal medium
(FE) having a first surface and a second surface so that the predetermined print starting
position (SP) of the medium (10) is past a predetermined distance from heating elements
(52) of a thermal printhead (51); (c) printing a first test pattern (T1) on the first
surface when the said edge (FE) of the medium (10) is detected by an edge detection
sensor (53) while feeding the medium (10); (d) measuring a first distance between
the said edge (FE) and the first test pattern (T1) by detecting the first test pattern
(T1) using the edge detection sensor (53); (e) rotating the thermal printhead (51)
to face the second surface; (f) feeding the thermal medium (10) so that the predetermined
print starting position (SP) of the medium (10) is past a predetermined distance from
the heating elements (52) of the thermal printhead (51); (g) printing a predetermined
second test pattern (T2) on the second surface when the said edge (FE) of the medium
(10) is detected by the edge detection sensor (53); and (h) measuring a second distance
between the said edge (FE) and the second test pattern (T2) by detecting the second
test pattern (T2).
[0011] Step (b) may further comprise the step of measuring a third distance by subtracting
the first distance from a distance between the front edge and the predetermined print
starting position, wherein a position where the medium is fed the third distance from
a point when the said edge is detected as the print starting position of the first
surface.
[0012] Step (g) may further comprise the step of calculating a fourth distance by subtracting
the second distance from the distance between the front edge and the predetermined
print starting position, wherein a position where the medium is fed the fourth distance
from a point when the said edge is detected as the print starting position of the
second surface.
[0013] The thermal printhead, a feeding roller, and the edge detection sensor may be sequentially
disposed in a printing direction, and steps (a) and (e) may be locating the said edge
between the feeding roller and the edge detection sensor.
[0014] The method may further comprise the steps of (h) feeding the thermal medium so that
the predetermined print starting position of the medium is past a predetermined distance
from the heating elements of the thermal printhead; (i) feeding the medium and starting
a printing operation of the first surface at the position where the medium is fed
the third distance from the point when the said edge is detected by the edge detection
sensor; (j) rotating the thermal printhead to face the second surface; (k) feeding
the medium so that the predetermined print starting position is past a predetermined
distance from the heating elements of the thermal printhead; and (1) feeding the medium
and starting a printing operation of the second surface at the position where the
medium is fed the fourth distance from when the said edge is detected by the edge
detection sensor.
[0015] Steps (i) and (1) may comprise detecting the said edge of the medium by the edge
detection sensor; and controlling a rotation of the feeding roller so that the said
edge can be separated at the third distance or the fourth distance from the sensor.
[0016] The thermal medium may include a print region and a tear-off region including the
said edge, and the print starting position may be formed at the tear-off region.
[0017] The edge detection sensor may be an optical sensor or other suitable sensing means.
[0018] Embodiments of the invention will now be described, by way of example only, with
reference to Figures 1 and 3 to9 of the accompanying drawings, in which:
Figure 1 is a cross-sectional view showing a conventional thermal medium;
Figure 2 is a view showing a structure of a conventional thermal printer;
Figure 3 is a view showing a thermal printer that is used in a method of printing
the thermal medium by aligning image according to an embodiment of the present invention;
Figure 4 is a schematic plan view showing a part of a device adopting the method of
printing the thermal medium by aligning image according to an embodiment of the present
invention;
Figure 5 is a schematic side view showing a part of the device shown in Figure 4;
Figure 6 is a view showing an example of the thermal medium used in an embodiment
of the present invention;
Figure 7 is a flow chart illustrating the method for printing on a thermal medium
by aligning the image according to an embodiment of the present invention;
Figures 8A through 8F illustrating the method for printing on the thermal medium by
aligning the image according to an embodiment of the present invention; and
Figure9 is a view illustrating a method for measuring a first distance and a second
distance according to an embodiment of the present invention.
[0019] Throughout the drawings, it should be understood that like reference numbers refer
to like features, structures and elements.
[0020] Hereinafter, a method for printing on a thermal medium by aligning an image according
to embodiments of the present invention will be described with reference to the accompanying
drawings.
[0021] Figure 3 is a view showing a thermal printer adapted for performing a method for
aligning an image on a thermal medium according to an embodiment of the present invention.
[0022] As shown in Figure 3, the thermal printer comprises at least a first path, a second
path, and a third path, and conveys a thermal medium through the above paths. A pickup
roller 72 picks up the medium 10 from a media storage unit 70 and conveys the medium
through the first path. The first path is a medium 10 supply path for moving the medium
10 toward the second path. The second path is an area where the medium 10 is back-fed
in a direction represented by arrow B and forward fed to a direction represented by
arrow F (printing direction) for a printing operation. After the printing operation
has been completed, the third path is a path by which the medium 10 is discharged
finally.
[0023] A media guide 65 is disposed between the first path and the third path. The media
guide 65 guides the medium 10 from the first path to the second path, and guides the
medium 10 from the second path to the third path. In addition, after the printing
operation, the media guide 65 guides the medium 10 from the second path to proceed
toward the third path only, and prevents the medium 10 from proceeding toward the
first path.
[0024] In the second path, an image is formed by an image forming unit 50. Before the images
are formed on the first and second surfaces of the medium 10, the locations of the
thermal printhead (TPH) 51 and the platen roller 55 of the image forming unit 50 should
be at predetermined locations. That is, if the image is formed on the first surface
of the medium 10, the TPH 51 should be located at position C in Figure 3. If the image
is formed on the second surface of the medium 10, the TPH 51 should be located at
position D. It is desirable that the location of the TPH 51 changes by rotating the
platen roller 55 and the TPH 51 centering on a rotary shaft of the platen roller 55.
The change of TPH 51 location is performed when the TPH 51 is not obstructed by the
medium 10, for example, before the medium 10 is supplied from the first path, or when
the medium 10 is not returned to the second path after being conveyed toward the third
path during the image formation on the first surface.
[0025] When the medium 10, after the first surface has been printed on, is backfed to the
second path, the image is formed on the second surface of the medium 10 by the rotated
TPH 51. In the above process, the medium 10 is gradually advanced by a conveying unit
40, discharged by a media discharging unit 60 after the image is formed on the second
surface. The conveying unit 40 comprises a feeding roller 41 that conveys the medium
10, and an idle roller 42 that pushes the medium 10 to enter between the feeding roller
41 and the idle roller 42 toward the feeding roller 41.
[0026] Reference numeral 53 denotes an optical sensor that detects an edge of the medium
10. The media discharging unit 60 includes a discharge roller 61 and an idle roller
62, and the discharge roller 61 and the pickup roller 72 that can also be formed integrally
using one roller having a combined function of picking up and discharging media 10.
[0027] Figure 4 is a schematic plan view showing a part of a device using the method for
printing on thermal media by aligning images according to an embodiment of the present
invention, and Figure 5 is a schematic side view showing the device of Figure 4.
[0028] In Figure 4, the distance between the feed roller 41 and heating element (refer to
reference numeral 52 of Figure 4) of the TPH 51 on the medium 10 can be different
depending on the surface of the medium 10 to be printed.
[0029] Referring to Figures 4 and 5, the TPH 51, the feeding roller 41, and the optical
sensor 53 are sequentially disposed in the printing direction of the medium. The thermal
medium 10, which enters between the platen roller 55 and the TPH 51, is controlled
by the rotation of the feeding roller 41.
[0030] In the TPH 51, a plurality of heating elements 52 are preferably arranged in a row
or a plurality of rows disposed perpendicular to the medium conveying direction. The
heating elements 52 emit heats for a predetermined time period and at a predetermined
temperature according to a signal voltage that corresponds to a particular colour.
[0031] The medium 10 is conveyed to the direction represented by the arrow B, that is, the
backfeeding direction, or to the direction represented by the arrow F, that is, the
printing direction by the feeding roller 41 depending upon the operation being performed.
An encoder disk wheel 45 is installed on an outer circumference of the feeding roller
41. Slits 45a are formed on an edge of the encoder disc wheel 45 at predetermined
intervals, and rotary encoder sensors 46 including a light emitting portion 46a and
a light receiving portion 46b are mounted on both sides of the slit 45a. The light
emitting unit 46a of the rotary encoder sensor 46 emits light at predetermined intervals,
and the light receiving unit 46b generates pulse signals whenever it receives light
through the slit 45a. A controller 80 counts the pulse signals to measure the conveyed
distance of the medium 10 that is conveyed by the feeding roller 41, and drives a
driving motor 47 to control the conveyed distance of the medium 10 that is conveyed
by the feeding roller 41. Reference numeral 82 denotes a look-up table (LUT).
[0032] The thermal printer includes a rotating unit 57 that rotates the TPH 51 and the platen
roller 55 to perform the printing process for the second surface after performing
the printing process for the first surface of the medium 10, and a vertical moving
unit 59 that either separates the TPH 51 from the printing path or pushes the TPH
51 close to the printing path. The vertical moving unit 59 separates the TPH 51 a
predetermined distance, for example, 1 to 2mm, from the platen roller 55 so that the
medium 10 can pass between the TPH 51 and the platen roller 55 when the medium 10
is backfed, preferably, to the third path.
[0033] In addition, the optical sensor 53 is disposed in front of the feeding roller 41
in the forward feeding direction, denoted by the arrow B, to transmit an optical output
value of the medium 10 conveyed thereunder to the controller 80, and the controller
80 determines the edge of the medium 10 using the transmitted optical output value.
[0034] Figure 6 is a view of an example of the thermal medium according to an embodiment
of the present invention.
[0035] Referring to Figure 6, the thermal medium 10 can be classified into a printing region
(PR), and tear-off regions to be removed after printing (TR1 and TR2). A transverse
length (L
1) of the PR is 6 inches and a longitudinal length (L
2) of the PR is 4 inches, and a transverse length (L
3) of the first tear-off region (TR1) is about 1 inch and a transverse length (L
4) of the second tear-off region (TR2) is 1/3 inch. Arrow F denotes the conveying direction
of the medium 10 during forward feeding for being printed. FE denotes a front edge,
and RE denotes a rear edge. In Figure 6, dotted lines denote tear-off lines, and dashed
dot lines denote starting and ending positions of the actual printing region for performing
borderless printing. Distance L5 is about 2 mm. In addition, SP denotes a printing
start position.
[0036] A printing method according to an embodiment of the present invention will be described
with reference to accompanying drawings.
[0037] Figure 7 is a flow chart illustrating a printing method according to an embodiment
of the present invention.
[0038] When a printing command is input into the controller 80 from a computer that is connected
with the printer, a sheet of thermal media 10 is picked up by the pickup roller 72
from the media container 70 and enters the first path (S101).
[0039] The medium 10 entering the first path is supplied to the feeding roller 41 by the
media guide 65, and the feeding roller 41 makes the medium 10 backfed to the second
path in the direction represented by the arrow B (S102). Here, the TPH 10 is raised
so that the medium 10 can pass between the TPH 51 and the platen roller 55 easily.
[0040] As shown in Figure 8A, it is desirable that the front edge (FE) of the medium is
located between the feed roller 41 and the optical sensor 53 after passing the optical
sensor 53. In addition, a print starting position (SP) of the medium 10 is past a
predetermined distance ahead of the lower portion of the heating element 52.
[0041] The TPH 51 is adhered to the medium 10, and the medium 10 is conveyed in the direction
represented by the arrow F to start the printing of the first surface (S103).
[0042] As shown in Figure 8B, when the optical sensor 53 detects the front edge (FE) of
the medium 10 (S104), the medium 10 is further fed a first distance D
1 stored in the LUT 82 so that the print starting position SP can be disposed under
the heating element 52 as shown in FIG. 8C (S105). That point is defined as the print
starting position of the first surface. The movement of the first distance D
1 is controlled by the rotary encoder sensor 46 from the point when the front edge
FE of the medium 10 is detected by the optical sensor 53.
[0043] In addition, colour image data corresponding to the print layer of the first surface,
for example, yellow and magenta image data, is transmitted from the controller 80
to the TPH 51 to perform the printing operation (S106).
[0044] When the printing process for the first surface is completed, the medium 10 is further
fed a predetermined distance forwardly so that the medium 10 does not contact the
image forming unit 50. In addition, the image forming unit 50 is rotated so that the
TPH 51 faces the second surface of the medium 10 (S107).
[0045] Next, a gap, through which the medium 10 can pass without resistance, is formed between
the platen roller 55 and the TPH 51 by lowering the TPH 51 slightly, and the medium
10 is backfed to the second path by the feeding roller 41 in preparation for printing
on the second surface (S108). Here, as shown in Figure 8D, it is desirable that the
front edge FE of the medium 10 be disposed between the feeding roller 41 and the optical
sensor 53 past the optical sensor 53. In addition, the print starting portion SP of
the medium 10 is past a predetermined distance from the heating element 52 of the
TPH 51.
[0046] The TPH 51 is adhered to the medium 10, and the medium 10 is conveyed in a direction
represented by the arrow F to start the printing operation on the second surface (S109).
[0047] In addition, as shown in Figure 8E, when the optical sensor 53 detects the front
edge FE of the medium 10 (S110), the medium 10 is further fed a second distance D
2 stored in the LUT 82 so that the print starting position SP is disposed under the
heating element 51 (S111). That point is defined as the print starting position for
the second surface. The movement of the medium 10 for the second distance D
2 is controlled by the rotary encoder sensor 46 from when the front edge (FE) of the
medium 10 is detected by the optical sensor 53.
[0048] Then, the controller 80 transmits colour image data corresponding to the printing
layer of the second surface, for example, cyan (C) image data, to the TPH 51 to perform
the printing process (S112).
[0049] When the printing process for the second surface is completed, the medium 10 is conveyed
to the third path, the conveying unit 40 stops conveying the medium 10 and the medium
10 is discharged out of the printer by the media discharge unit 60 (S113).
[0050] In the above embodiment, the first and second distances D
1 and D
2 are first measured and then stored in the LUT 82.
[0051] Figure 9 is a view illustrating a method for measuring the first and second distances
D
1 and D
2.
[0052] Referring to Figure 9, when the front edge FE of the medium 10 is detected by the
optical sensor 53, the distance between the heating element 52 of the TPH 51 and the
front edge FE can be different when the first surface is printed and when the second
surface is printed. For example, in printing the first surface, the print starting
position SP is separated by the first distance D
1 from the heating element 52 of the TPH 51 at the point when the front edge FE of
the medium 10 is detected during the printing of the first surface of the medium 10.
While, in printing the second surface, the heating element 52 is separated by the
second distance D
2 from the print starting position SP when the front edge (FE) of the medium 10 is
detected by the optical sensor 53. When the front edge (FE) is detected, predetermined
test patterns T1 and T2 are printed on the first and second surfaces, respectively,
during the respective printing operations. The medium 10 is backfed so that test patterns
T1 and T2, respectively, can be detected by optical sensor 53 prior to the respective
printing operation.
[0053] In addition, the first distance D
1 is calculated by subtracting the distance measured between the front edge FE and
the test pattern T
1 from a length (L
3 - L
5) between the front edge FE and the print starting position SP, and the second distance
D
2 is calculated by subtracting the measured distance between the front edge FE and
the test pattern T
2 from the length (L
3 - L
5). The measured first and second distances D
1 and D
2 are stored in the LUT 82, thus the measured first and second distances D
1 and D
2 can be used in the actual printing process.
[0054] According to the printing method of an embodiment of the present invention, the print
starting position is aligned to perform the dual-side printing operation while feeding
the thermal medium in the printing direction. Therefore, the image aligning can be
made accurately.
[0055] While the present invention has been particularly shown and described with reference
to exemplary embodiments thereof, it will be understood by those of ordinary skill
in the art that various changes in form and details may be made therein without departing
from the scope of the present invention as defined by the following claims.
1. A method of printing a thermal medium by aligning image, the method comprising:
(a) defining a predetermined print starting position (SP) on a thermal medium (10)
a predetermined distance (L3-L5) from one edge (FE) of the thermal medium (10);
(b) feeding said thermal medium (10) having a first surface and a second surface so
that the predetermined print starting position (SP) of the medium (10) is past a predetermined
distance from heating elements (52) of a thermal printhead (51);
(c) printing a first test pattern (T1) on the first surface when the said edge (FE)
of the medium (10) is detected by an edge detection sensor (53) while feeding the
medium (10);
(d) measuring a first distance between the said edge (FE) and the first test pattern
(T1) by detecting the first test pattern (T1) using the edge detection sensor (53);
(e) rotating the thermal printhead (51) to face the second surface;
(f) feeding the thermal medium (10) so that the predetermined print starting position
(SP) of the medium (10) is past a predetermined distance from the heating elements
(52) of the thermal printhead (51);
(g) printing a predetermined second test pattern (T2) on the second surface when the
said edge (FE) of the medium (10) is detected by the edge detection sensor (53); and
(h) measuring a second distance between the said edge (FE) and the second test pattern
(T2) by detecting the second test pattern (T2).
2. The method of claim 1, wherein step (c) further comprises calculating a third distance
D1 by subtracting the first distance from the predetermined distance (L3-L5) between the said edge (FE) and the predetermined print starting position (SP), wherein
a position where the medium (10) is fed the third distance D1 from a point when the said edge (FE) is detected as the print starting position (SP)
of the first surface.
3. The method of claim 2, wherein step (h) further comprises calculating a fourth distance
D2 by subtracting the second distance from the predetermined distance (L3-L5) between the said edge (FE) and the predetermined print starting position (SP), wherein
a position where the medium (10) is fed the fourth distance D2 from a point when the said edge (FE) is detected as the print starting position (SP)
of the second surface.
4. The method of claim 3, wherein the thermal printhead (51), a feeding roller (41),
and the edge detection sensor (53) are sequentially disposed in a printing direction,
and steps (b) and (f) are feeding the medium (10) until the said edge (FE) of the
medium (10) is between the feeding roller (41) and the edge detection sensor (53).
5. The method of claim 4, further comprising the steps of:
(i) feeding the thermal medium (10) so that the predetermined print starting position
(SP) of the medium (10) is past a predetermined distance from the heating elements
(52) of the thermal printhead (51);
(j) feeding the medium (10) and starting a printing operation on the first surface
at the position where the medium (10) is fed the third distance from the point when
the said edge (FE) is detected by the edge detection sensor (53);
(k) rotating the thermal printhead (51) to face the second surface;
(l) feeding the medium (10) so that the predetermined print starting position (SP)
is past a predetermined distance from the heating elements (52) of the thermal printhead
(51); and
(m) feeding the medium (10) and starting a printing operation of the second surface
at the position where the medium (10) is fed the fourth distance from when the said
edge (FW) is detected by the edge detection sensor (53).
6. The method of claim 5, wherein steps (j) and (m) comprise detecting the said edge
(FE) of the medium (10) by the edge detection sensor (53), and controlling a rotation
of the feeding roller (41) so that the said edge (FE) can be separated the third distance
or the fourth distance from the edge detection sensor (53).
7. The method of claim 5, wherein the thermal medium (10) includes a print region (PR)
and a tear-off region (TR1) including the said edge (FE), and the print starting position
(SP) is formed at the tear-off region (TR1).
8. The method of claim 1, wherein the edge detection sensor (53) is an optical sensor.
1. Verfahren zum Bedrucken eines thermischen Mediums mittels Bildausrichtung, wobei das
Verfahren die folgenden Schritte beinhaltet:
(a) Definieren einer vorbestimmten Druckstartposition (SP) auf einem thermischen Medium
(10) in einer vorbestimmten Distanz (L3-L5) von einem Rand (FE) des thermischen Mediums (10);
(b) Vorschieben des genannten thermischen Mediums (10) mit einer ersten Fläche und
einer zweiten Fläche, so dass die vorbestimmte Druckstartposition (SP) des Mediums
(10) eine vorbestimmte Distanz an Heizelementen (52) eines Thermodruckkopfes (51)
vorbei liegt;
(c) Drucken eines ersten Testmusters (T1) auf die erste Fläche, wenn der genannte
Rand (FE) des Mediums (10) von einem Randerfassungssensor (53) erfasst wird, während
das Medium (10) vorgeschoben wird;
(d) Messen einer ersten Distanz zwischen dem genannten Rand (FE) und dem ersten Testmuster
(T1) durch Erfassen des ersten Testmusters (T1) mit dem Randerfassungssensor (53);
(e) Drehen des Thermodruckkopfes (51), so dass er der zweiten Fläche zugewandt ist;
(f) Vorschieben des thermischen Mediums (10), so dass die vorbestimmte Druckstartposition
(SP) des Mediums (10) eine vorbestimmte Distanz an den Heizelementen (52) des Thermodruckkopfes
(51) vorbei liegt;
(g) Drucken eines vorbestimmten zweiten Testmusters (T2) auf die zweite Fläche, wenn
der genannte Rand (FE) des Mediums (10) vom Randerfassungssensor (53) erfasst wird;
und
(h) Messen einer zweiten Distanz zwischen dem genannten Rand (FE) und dem zweiten
Testmuster (T2) durch Erfassen des zweiten Testmusters (T2).
2. Verfahren nach Anspruch 1, wobei Schritt (c) ferner das Berechnen einer dritten Distanz
D1 durch Subtrahieren der ersten Distanz von der vorbestimmten Distanz (L3-L5) zwischen dem genannten Rand (FE) und der vorbestimmten Druckstartposition (SP) beinhaltet,
wobei eine Position, an der das Medium (10) ab einem Punkt, an dem der genannte Rand
(FE) als die Druckstartposition (SP) der ersten Fläche erfasst wird, um die dritte
Distanz D1 vorgeschoben wird.
3. Verfahren nach Anspruch 2, wobei Schritt (h) ferner das Berechnen einer vierten Distanz
D2 durch Subtrahieren der zweiten Distanz von der vorbestimmten Distanz (L3-L5) zwischen dem genannten Rand (FE) und der vorbestimmten Druckstartposition (SP) beinhaltet,
wobei eine Position, an der das Medium (10) ab einem Punkt, an dem der genannte Rand
(FE) als die Druckstartposition (SP) der ersten Fläche erfasst wird, um die vierte
Distanz D2 vorgeschoben wird.
4. Verfahren nach Anspruch 3, wobei der Thermodruckkopf (51), eine Vorschubwalze (41)
und der Randerfassungssensor (53) sequenziell in Druckrichtung angeordnet sind und
das Medium (10) in den Schritten (b) und (f) vorgeschoben wird, bis der genannte Rand
(FE) des Mediums (10) zwischen der Vorschubwalze (41) und dem Randerfassungssensor
(53) liegt.
5. Verfahren nach Anspruch 4, das ferner die folgenden Schritte beinhaltet:
(i) Vorschieben des thermischen Mediums (10), so dass die vorbestimmte Druckstartposition
(SP) des Mediums (10) eine vorbestimmte Distanz an den Heizelementen (52) des Thermodruckkopfes
(51) vorbei liegt;
(j) Vorschieben des Mediums (10) und Starten eines Druckvorgangs auf der ersten Fläche
an der Position, an der das Medium (10) um die dritte Distanz von dem Punkt, an dem
der genannte Rand (FE) vom Randerfassungssensor (53) erfasst wird, vorgeschoben wird;
(k) Drehen des Thermodruckkopfes (51), so dass er der zweiten Fläche zugewandt ist;
(l) Vorschieben des Mediums (10), so dass die vorbestimmte Druckstartposition (SP)
eine vorbestimmte Distanz an den Heizelementen (52) des Thermodruckkopfes (51) vorbei
liegt; und
(m) Vorschieben des Mediums (10) und Starten eines Druckvorgangs der zweiten Fläche
an der Position, an der das Medium (10) um die vierte Distanz vorgeschoben wird, ab
dem Punkt, an dem der genannte Rand (FW) von dem Randerfassungssensor (53) erfasst
wird.
6. Verfahren nach Anspruch 5, wobei die Schritte (j) und (m) das Erfassen des genannten
Randes (FE) des Mediums (10) durch den Randerfassungssensor (53) und das Steuern einer
Rotation der Vorschubwalze (41) beinhalten, so dass der genannte Rand (FE) um die
dritte Distanz oder die vierte Distanz vom Randerfassungssensor (53) getrennt werden
kann.
7. Verfahren nach Anspruch 5, wobei das thermische Medium (10) eine Druckregion (PR)
und eine Abreißregion (TR1) einschließlich des genannten Randes (FE) aufweist und
die Druckstartposition (SP) an der Abreißregion (TR1) ausgebildet ist.
8. Verfahren nach Anspruch 1, wobei der Randerfassungssensor (53) ein optischer Sensor
ist.
1. Procédé d'impression d'un support thermique par alignement de l'image, le procédé
comprenant les étapes consistant à :
(a) définir une position de début d'impression prédéterminée (SP) sur un support thermique
(10), à une distance prédéterminée (L3-L5) d'un bord (FE) du support thermique (10) ;
(b) faire avancer ledit support thermique (10) ayant une première surface et une deuxième
surface de sorte que la position de début d'impression prédéterminée (SP) du support
(10) ait dépassé une distance prédéterminée par rapport aux éléments chauffants (52)
d'une tête d'impression thermique (51) ;
(c) imprimer un premier motif d'essai (T1) sur la première surface lorsque ledit bord
(FE) du support (10) est détecté par un capteur de détection du bord (53) pendant
l'avance du support (10) ;
(d) mesurer une première distance entre ledit bord (FE) et ledit premier motif d'essai
(T1) en détectant le premier motif d'essai (T1) au moyen du capteur de détection du
bord (53) ;
(e) faire pivoter la tête d'impression thermique (51) pour qu'elle fasse face à la
deuxième surface ;
(f) faire avancer le support thermique (10) de telle sorte que la position de début
d'impression prédéterminée (SP) du support (10) ait dépassé une distance prédéterminée
par rapport aux éléments chauffants (52) de la tête d'impression (51) ;
(g) imprimer un deuxième motif d'essai prédéterminé (T2) sur la deuxième surface lorsque
ledit bord (FE) du support (10) est détecté par le capteur de détection du bord (53)
; et
(h) mesurer une deuxième distance entre ledit bord (FE) et le deuxième motif d'essai
(T2) en détectant le deuxième motif d'essai (T2).
2. Procédé selon la revendication 1, dans lequel l'étape (c) comprend en outre le calcul
d'une troisième distance D1 en soustrayant la première distance de la distance prédéterminée (L3-L5) entre ledit bord (FE) et la position de début d'impression prédéterminée (SP), dans
lequel une position où le support (10) est avancé de la troisième distance D1 par rapport à un point où ledit bord (FE) est détecté comme position de début d'impression
(SP) de la première surface.
3. Procédé selon la revendication 2, dans lequel l'étape (h) comprend en outre le calcul
d'une quatrième distance D2 en soustrayant la deuxième distance de la distance prédéterminée (L3-L5) entre ledit bord (FE) et la position de début d'impression prédéterminée (SP), dans
lequel une position où le support (10) est avancé d'une quatrième distance D2 par rapport à un point où ledit bord (FE) est détecté comme position de début d'impression
(SP) de la deuxième surface.
4. Procédé selon la revendication 3, dans lequel la tête d'impression thermique (51),
un rouleau d'avance (41) et le capteur de détection du bord (52) sont disposés séquentiellement
dans une direction d'impression, et les étapes (b) et (f) font avancer le support
(10) jusqu'à ce que ledit bord (FE) du support (10) soit entre le rouleau d'avance
(41) et le capteur de détection du bord (53).
5. Procédé selon la revendication 4, comprenant en outre les étapes consistant à :
(i) faire avancer le support thermique (10) de telle sorte que la position de début
d'impression prédéterminée (SP) du support (10) ait dépassé une distance prédéterminée
par rapport aux éléments chauffants (52) de la tête d'impression thermique (51) ;
(j) faire avancer le support (10) et démarrer une opération d'impression sur la première
surface à la position où le support (10) est avancé de la troisième distance par rapport
au point où ledit bord (FE) est détecté par le capteur de détection du bord (53) ;
(k) faire pivoter la tête d'impression thermique (51) pour qu'elle fasse face à la
deuxième surface ;
(l) faire avancer le support (10) de telle sorte que la position de début d'impression
prédéterminée (SP) ait dépassé une distance prédéterminée par rapport aux éléments
chauffants (52) de la tête d'impression thermique (51) ; et
(m) faire avancer le support (10) et démarrer une opération d'impression de la deuxième
surface à la position où le support (10) est avancé de la quatrième distance par rapport
au point où ledit bord (FW) est détecté par le capteur de détection du bord (53).
6. Procédé selon la revendication 5, dans lequel les étapes (j) et (m) comprennent la
détection dudit bord (FE) du support (10) par le capteur de détection du bord (53),
et le contrôle de la rotation du rouleau d'avance (41) de sorte que ledit bord (FE)
puisse être séparé de la troisième distance ou de la quatrième distance par rapport
au capteur de détection du bord (53).
7. Procédé selon la revendication 5, dans lequel le support thermique (10) comprend une
zone d'impression (PR) et une zone de découpage (TR1) comprenant ledit bord (FE),
et la position de début d'impression (SP) est formée au niveau de la zone de découpage
(TR1).
8. Procédé selon la revendication 1, dans lequel le capteur de détection du bord (53)
est un capteur optique.